When errors occur in either the confirm_data or insert_data action, redirect to
the choose_global_data_values action (now that we never skip this page) rather
than back to the HTTP_REFERRER.  This reduces or eliminates the chance of a
redirect loop (eliminating the problem mentioned in Redmine Task #2515) and is
probably what we want to do anyway.
Added validation of dates that are entered interactively.
When converting data values, skip conversion if data is nil.
Added page for viewing trait-covariate associations.
Fixed typo in exception name.
Added link to list of trait-covariate associations.
Validate access level when entered interactively.  Copy
'choose_global_data_values' form data to session *before* validating the values
entered so that if an exception is thrown and we return to the form, it will be
properly populated.
Validate access level more completely in model.
Bulk Upload: Don't select a default access level in the 'choose global data values' form.
Removed comment.
Added a new spec file with new bulk upload integration tests.  Corrected form
labels on 'choose_global_data_values' page to get tests that rely on
properly-labelled from controls to work.